From Our Berlin Correspondent.
Page 6
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The Daimler Benzol Carburetter.
The Geist Electric Company, of Cologne, which entered a petrol-electric lorry for the recent Industrial Vehicle Trials, yet without achieving any success, since a broken armature put the vehicle out of action, announces a net profit of ;65,454 for 1906-7, which yields a dividend of 8 per cent., as in 1905-6.
Another Bavarian Motorbus Line.
On April 1st, Tgo8, a motorbus line will be opened between Passau and Zwiesel, via Tittling and Schoneberg-. This particular district, which is very picturesque, attracts numerous tourists in the spring and summer months, so that the line will doubtless show a profit.
Saurer and " Safir " Combination.
The Saurer works and its Zurich licensee, the " Safir " Automobilfabrik, have arranged for a fusion of interests so far as the German market is concerned. Both firms were represented in the recent industrial trials, and did so well that five out of their six entries secured gold medals. Switzerland occupies premier position amongst countries exporting industrial automobiles to Germany, and this fusion will doubtless oive an additional fillip to the trade. Their success in the trials will be worked for all it is worth.
A Saurer Bus in the Tyrol.
A short time ago I reported the opening of a motorbus line between Neumarkt and Predazzo, in the Tyrolean Alps, by the Austrian Post Office, who purchased the chassis from the Austrian Daimler Company. I note that a Sauree omnibus has been on trial in this district, and the " Bozener Zeitung" prints highly favourable comments on the working qualities of this make, especially on the effectiveness of the air-brake employed by the firm. The Saurer was called upon to undertake some very stiff climbs.
An Omnibus on the "Mixed" System for Berlin.
Notwithstanding that the Grosse Berliner Motoromnibus-G esellschaf L's
fleet of motorbuses is to a great extent still in dock, neither of its two initial lines having yielded any profit—as a matter of fact, receipts over the routes the Gesellschaft had no option but to take, are about a third of the working costs l—the Gesellschaft purposes giving a trial to a bus on the " mixed " system, constructed by Siemens and Schuckert, a system which, whatever advantages it may have to offer in smoother working and easier transition from speed to speed, cannot he said to be any cheaper. In the event of the trial vehicle showing points of advantage over the petrol buses now in use (Marienfeldes and N.A.G.'s) the "Grosse "will in future order "mixed" types. But, as implied, the actual con_ dition of affairs does not lead one to conclude that any extension of its motorbus lines • will take place in the near future. The company here referred
to is the off-shoot of Berlin's great tramcar company, not the Berlin General Omnibus Company.
Motorbus Lines.
The General Potsdam Motorbus Company has been dissolved, in accordance with a vote at a general meeting of shareholders. Stoewer vehicles worked this service, although the failure of the concern is due, not to the unsatisfactory working of these vehicles, but to inadequate receipts. In Bad Durkheim (north-west of Mannheim), Herr Limbacher, a carrier, purposes linking up Eisenberg and Enkenbach by means of in
A Benzol Carburetter.
Included in the list of gold medallists in the recent German, commercialmotor trials was a Daimler (in class 4) which ran throughout on benzol fuel. The announcement appeared in " THE COMMERCIAL MOTOR " Of the 31st Ultimo and in the following week's issue a photograph of the wagon was reproduced. I am now able to add a few particulars and drawings of the carburetter as fitted to that vehicle.
Figure i shows a vertical section through the carburetter. The principle underlying its construction consists of the simultaneous control of the main and the auxiliary supplies of air, the rate at which the fuel is delivered by the jet, and the admission of the mixture to the cylinders. All these operations are effected by the single piston, or cylindrical valve (A), which is regulated by the governor or by means of a hand lever. Describing each of these operations in turn, the action of the carburetter is as follows :
r. Control of the main supply of air :The main air passage (B) is of conical formation and, as the valve is raised or lowered, the area of the passage between the internal face of that cone and the external face. of the jet-piece is
varied. When the engine is at rest, the valve is at its highest position and, therefore, the area is then greatest.
2. Control of the auxiliary air supply :—As the piston (A) is caused to descend, the area of the main, air inlet is gradually decreased and the area of the auxiliary, air-inlet ports (C) is, at the same time, increased.
3. Control of the rate of discharge of the fuel from the jet (D) :—The action of the rising or falling valve (A), and the variation of the area (B) around the jet, causes a corresponding fluctuation in the degree of vacuum created about the jet-piece. The more rarified the air becomes at that point, the faster will the fuel flow.
4. Control of the mixture to the engine :—This is effected by the variation of the area of the ports in the upper part of the valve.
The excellent results attained with this carburetter are best seen when its extreme points of regulation are separately examined. When the valve is at its lowest position, it may be assumed that the air sweeps past the jet at a constant velocity, that it takes up fuel at an even rate, and that it draws in air through the auxiliary air ports at such a rate as to produce an economical mix
ture. The ports through which the mixture is admitted to the cylinders are, of course, open to their fullest extent when the valve is in the lowest position. Now, one may take the other extreme. When the valve is in its highest position, the velocity of the air past the jet is at its lowest ; the auxiliary air meets with, now, the greatest resistance, by reason of the decreased area of the ports (.0; and the ports in the upper part of the valve check the flow of gas to the cylinders. It has thus been found quite easy to throttle the engine down to 2oor.p.m. and vet to maintain steady running without fear of a misfire or stop.
The temperature of the air is raised in its passage to the lower part of the casting surrounding the jet chamber, and the tipper part of the valve is surrounded by a jacket through which the exhaust gases are caused to pass, as shown in Figure 2, which view also shows the lever and rod by means of which the valve is operated.